The 900's are bright and bass heavy if I remember correctly. I would say the Rooth LS8 is close to that and the JH16 is also similar as is the Hidition NT-6 pro. I have reviewed all three, so hopefully my reviews will help with your decision.

The JH16Pro, UE11Pro and Westone ES5 are close match for the Pro900 type soundsignature.

From what I know (and the aud-5X sounding somewhat similar to the ES5 in the mids and treble), the JH16 and ES5 don't sound alike, so please let me know your experience comparing the two. Also, wouldn't the UE18 also fall into having a similar type of sound signature?

The JH16Pro, UE11Pro and Westone ES5 are close match for the Pro900 type soundsignature.

The Pro 900 had very recessed mids, and quite a sibilant treble. Are you saying that the customs you recommend here are all of that ilk? I don't recall reading that about any of those.... Strange recommendations.